<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <style>
    table,th,td{
        border: 1px solid #333;

    }
    table{
        width: 150px;
         /* 边框折叠   (核心) */
         border-collapse: collapse;



    }
    </style>
    <title>Document</title>
</head>
<body>
    <!-- 跨越列的表格 colspan -->
    <table>

       <thead>
            <tr>
                <th colspan="3">商城</th>

            </tr>
          
       </thead>

       <tbody>

        <tr>
            <td>小米</td>
            <td>小米</td>
            <td>小米</td>
            
        </tr>
        <tr>
                <td>小米</td>
                <td>小米</td>
                <td>小米</td>
                
            </tr>
       </tbody>


    </table>
</body>
</html>